<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>定时器示例</title>
</head>
<body>

<input type="text" id="result">

<input type="button" value="开始" >
<input type="button" value="结束" >

<script>
    // write your code here
    // ......
    var value=document.getElementsId("result");
    var start_btn=document.getElementsByTagName("input")[1];
    var end_btn=document.getElementsByTagName("input")[2];

    start.onclick=function () {

    }
</script>
</body>
</html>